1. Field of the Invention
This invention relates to a heating device for a glove. More particularly, this invention relates to a heating device to be inserted in a skiing glove.
2. Description of the Prior Art
Heretofore, various types of heating devices have been applied to garments or other apparel as an added protection for a wearer of the garment against cold temperatures. These heating devices seek to add the comfort of additional heat without detracting from the aesthetic or functional qualities of the garment. The heating devices usually include a power supply such as a battery, to supply electrical energy to a coiled heating unit for heating purposes. In these cases, there are two competing considerations, namely, the power requirements of the heating device and the amount of heat provided by the heating device. The larger the power supply, the more power can be provided to the coiled heating unit and to the wearer. Conversely, the size of the power supply impacts the desirability of the heating device since larger power supplies will be heavier and more cumbersome to the wearer.
Independent of these two considerations is the concern of creating a heating device that will be able to withstand the natural movements of the body and not break with the stresses induced by the wearer's actions. Operation of a heating device depends on maintaining electrical connections between the power supply and the heating units as well as the integrity of the heating units themselves. Protecting the heating device often requires increasing the amount or thickness and rigidity of the material encasing the electrical connections to buffer against the bending and creasing of the hand. The additional material, however, decreases the flexibility and comfortability of the heating device.
As applied to garments to cover the hand, certain heating devices have emphasized different goals. For example, as described in U.S. Pat. No. 4,764,665, one prior art device has implemented a heating unit that spans the entire length of the hand. This construction is intended to supply uniform heat for the entire hand, but has a large power requirement. The heating device is also more prone to be broken with the movements of the hand since each crease and bend will subject the device to stress.
U.S. Pat. No. 4,021,640 describes a heating device which is intended to reduce the amount of area to be heated and thus the power required by heating only the fingertips of a user. The heating device employs heating units located at the fingertips and formed of resistance heating elements encased in plastic material. The connecting wires for the heating units are lined on the back of the hand and extend over the fingertips to the fingertip pads. Insulating strips separate the heating units and the corresponding wires from the skin. The insulating strips also protect the back of the hand from the external temperatures.
This construction, however, causes stress on the device and would be uncomfortable for the wearer. By extending the insulating strips over the back of the hand, the strips and the underlying wires must stretch with every bending of the hand and fingers along their respective joints. The stretching of the insulating material would cause the material to rub against the hand directly causing discomfort to the knuckles and finger nails of the hand. This rubbing will also restrict the movement of the hand. The heating units can also become displaced since the insulating strips are being stretched. The integrity of the electrical connections can become more easily broken with the stretching of the insulation strips and the underlying wires.
In addition, using plastic may also cause discomfort due to the "flare-up" of the plastic along the edges. This "flare-up" occurs when the material is bent in one direction. While the plasitc will bend in that direction, the edges of the crease will "flare-up" in the opposite direction of the bend in the material. These "flared-up" edges are relatively hard and inflexible which cause discomfort to the wearer and can distort the desired shape of the material.